Road pricing has been proposed that bills vehicles traveling in a certain target region in order to relieve traffic congestion and reduce air pollution. For example, Japanese Patent Laying-Open No. 2005-274213 (Patent Document 1) describes a navigation system that executes route setting in consideration of an area regulated by road pricing (hereinafter referred to as a road pricing area).
Particularly, in the navigation system of Patent Document 1, in route setting, if an area used for route calculation includes a road pricing area, a determination is made whether entrance into the road pricing area is permitted or not based on permission information (a road pricing area under entrance permission and its permission period), and then a route is set which avoids a road pricing area having been determined that entrance thereto is not permitted. Accordingly, route calculation can be automatically executed avoiding such a situation that a vehicle will be billed for passage through the road pricing area with an area license invalidated.
Japanese Patent Laying-Open No. 7-107617 (Patent Document 2) describes a hybrid vehicle that, when traveling along a determined traveling route, allows for traveling in a traveling mode in accordance with a traveling environment, specifically, a motor mode of traveling with a motor alone using a battery as a power source without using the driving force of an engine.
Particularly, the hybrid vehicle described in Patent Document 2, when a driver selects a partial-area zero emission mode in accordance with driver's mode selection, travels in a densely populated area or a gas regulated area with the motor mode applied. When the driver selects a total zero emission mode, a total traveling distance is calculated from a traveling route retrieved as a result of route searching, and a determination is made whether or not the vehicle can travel the total traveling distance in the motor mode depending on the current battery state of charge, so that the necessity for charging is determined. Further, it is described that, when charging is necessary, a determination is made whether or not there is a charging station on the traveling route, and when there is a charging station, the driver receives an inquiry by an audio output or a display about whether or not he/she intends to charge the battery.
Furthermore, Japanese Patent Laying-Open No. 10-170293 (Patent Document 3) describes a route searching device for an electric vehicle for searching for an optimum leading route to a destination in consideration of the charge of the electric vehicle. Particularly, the configuration described in Patent Document 3 searches for a leading route to a destination in consideration of the charge of an on-vehicle battery, based on road map data containing information on charging stations.    Patent Document 1: Japanese Patent Laying-Open No. 2005-274213    Patent Document 2: Japanese Patent Laying-Open No. 7-107617    Patent Document 3: Japanese Patent Laying-Open No. 10-170293